The instant invention relates to granular detergent compositions which are resistant to granule lumping, said product exhibiting free-flowing granules upon pouring.
Recent attempts have been made to eliminate phosphate builders from detergent compositions because of the ability of these materials to act as a nutrient in promoting the growth of algae. As a consequence of the possible ecological effects of the continued use of phosphate builders in substantial quantities, attempts have been made to materially reduce or eliminate the need for phosphate salts in commercial detergent compositions.
A significant drawback in the elimination of phosphate builders from detergent products is that non-phosphate built products have poorer lumping and caking properties. More particularly, non-phosphate built products lack the capacity under conditions of high humidity and temperature to maintain their discrete granular form. A phosphate built product such as one employing sodium tripolyphosphate has a tendency to act as a moisture sink under conditions of high humidity, thereby lowering the caking effects upon the detergent granules Non-phosphate built products, however, such as those employing water-soluble salts of carbonates, bicarbonates, silicates, citrates and sesquicarbonates, while having a certain tendency to act as a moisture sink, do not perform as well in that capacity as phosphates. The use of a non-phosphate builder under conditions of high humidity results in a sticky, non-free-flowing product in a short period of time after the detergent package has been opened. Under very high humidity conditions a non-phosphate built product may cake to such an extent that a substantial amount of the detergent product cannot be removed from the package.
In order to compensate for the loss of the effective moisture sink provided by the phosphate builders, it has been suggested to use a more protective packaging material for the detergent composition. The use of a more humidity resistant packaging suffers from the defects of increased cost and the protection is substantially lessened upon the consumer's opening of the package. Prior art methods suggested to reduce the caking tendency of non-phosphate products include the use of toluene sulfonate or sodium sulfosuccinate as anti-caking agents. Sodium sulfosuccinate is a relatively expensive material to use while toluene sulfonate in a non-phosphate product may actually aggravate caking.
As an alternative to the inclusion of a phosphate builder moisture sink, special packaging or the use of other anti-caking agents, the applicants have found that the salts of benzoic acid are employed as effective anti-caking agents.
Accordingly, it is an object of the present invention to provide a non-phosphate detergent granule which is resistant to humidity caking.
It is a further object of the present invention to provide a non-phosphate detergent granule which requires less special packaging to ensure a free-flowing product.
It has been surprisingly discovered that the addition of salts of benzoic acid when thoroughly mixed in the detergent composition will give a granular detergent with exceptional pourability, storage stability, and acceptable caking properties.
The above-described desirable effects are most noticeably observed in a non-phosphate detergent granule which does not contain toluene sulfonate. In products in which toluene sulfonate must be used for other purposes, such as to reduce acid mix viscosity, the salts of benzoic acid taught in this patent minimize the tendency of the toluene sulfonate to cause a sticky, non-free-flowing product. Detergent compositions utilizing benzoic acid as a viscosity aid to reduce acid mix viscosity are described in the concurrently filed and commonly assigned U.S. Pat. applications of J. A. Sagel and C. E. Weber having Ser. No. 523,392 and a filing date of Nov. 13, 1974 and Ser. No. 523,390 and a filing date of Nov. 13, 1974 herein incorporated by reference.